The present invention relates generally to the field of advanced thin film deposition methods commonly used in the semiconductor, data storage, flat panel display, as well as allied or other industries. More particularly, the present invention relates to an in-situ preclean apparatus and technique suitable for cleaning and treatment of high aspect ratio features prior to the deposition of conductive, semi-conductive, and non-conductive thin films via modulated ion-induced atomic layer deposition (MII-ALD).